From 959ea26816ad4eb700d5026045777b1697a9a3c3 Mon Sep 17 00:00:00 2001
From: Alessandro Decina <alessandro.d@gmail.com>
Date: Thu, 6 Jan 2022 09:16:50 +1100
Subject: [PATCH] Re-enable LTO (#22287)

LTO seems to work fine now. It was possibly fixed by either the LLVM13 upgrade
or by https://github.com/alessandrod/rust/commit/b2ed47a92538161e03ae0a4ed5b81c8551054065,
which fixed a LTO issue with tests.
---
 sdk/bpf/env.sh                  |  2 --
 sdk/cargo-build-bpf/src/main.rs | 29 ++++++++++++-----------------
 2 files changed, 12 insertions(+), 19 deletions(-)

diff --git a/sdk/bpf/env.sh b/sdk/bpf/env.sh
index 55a49f9ea2..3bdf0555f8 100644
--- a/sdk/bpf/env.sh
+++ b/sdk/bpf/env.sh
@@ -14,5 +14,3 @@ export CC="$bpf_sdk/dependencies/bpf-tools/llvm/bin/clang"
 export AR="$bpf_sdk/dependencies/bpf-tools/llvm/bin/llvm-ar"
 export OBJDUMP="$bpf_sdk/dependencies/bpf-tools/llvm/bin/llvm-objdump"
 export OBJCOPY="$bpf_sdk/dependencies/bpf-tools/llvm/bin/llvm-objcopy"
-
-export RUSTFLAGS="${RUSTFLAGS} -C lto=no"
diff --git a/sdk/cargo-build-bpf/src/main.rs b/sdk/cargo-build-bpf/src/main.rs
index 2dcac2058d..99163a823e 100644
--- a/sdk/cargo-build-bpf/src/main.rs
+++ b/sdk/cargo-build-bpf/src/main.rs
@@ -515,25 +515,20 @@ fn build_bpf_package(config: &Config, target_directory: &Path, package: &cargo_m
     env::set_var("AR", llvm_bin.join("llvm-ar"));
     env::set_var("OBJDUMP", llvm_bin.join("llvm-objdump"));
     env::set_var("OBJCOPY", llvm_bin.join("llvm-objcopy"));
-    const RF_LTO: &str = "-C lto=no";
-    let mut rustflags = match env::var("RUSTFLAGS") {
-        Ok(rf) => {
-            if rf.contains(&RF_LTO) {
-                rf
-            } else {
-                format!("{} {}", rf, RF_LTO)
-            }
+
+    if let Ok(mut rustflags) = env::var("RUSTFLAGS") {
+        if cfg!(windows) && !rustflags.contains("-C linker=") {
+            let ld_path = llvm_bin.join("ld.lld");
+            rustflags = format!("{} -C linker={}", rustflags, ld_path.display());
         }
-        _ => RF_LTO.to_string(),
+
+        if config.verbose {
+            println!("RUSTFLAGS={}", rustflags);
+        }
+
+        env::set_var("RUSTFLAGS", rustflags);
     };
-    if cfg!(windows) && !rustflags.contains("-C linker=") {
-        let ld_path = llvm_bin.join("ld.lld");
-        rustflags = format!("{} -C linker={}", rustflags, ld_path.display());
-    }
-    if config.verbose {
-        println!("RUSTFLAGS={}", rustflags);
-    }
-    env::set_var("RUSTFLAGS", rustflags);
+
     let cargo_build = PathBuf::from("cargo");
     let mut cargo_build_args = vec![
         "+bpf",